Into the Caverns

January and I completed our Sidemount/Intro to Tech course and have moved on to Cavern! Hence the lack of updates for the last week. 

Intro to Tech was such a great learning experience and has definitely improved my diving more than any class I've taken so far, though at times it could be a bit frustrating, particularly when I couldn't quite get my gear-laden body to move exactly the way I needed it to in the water. It's amazing how hovering at a depth of exactly 11ft while performing a light failure drill can be so tiring. Every time I would sink down to 12ft or accidentally take too large of a breath and float up to 11ft, Arja, our instructor, would wag her finger at me as if scolding me for my poor buoyancy. But whenever I started to feel distracted or overwhelmed I'd take a timeout and spend a few seconds watching the snorkelers a few feet above us doing their goofy dog paddles around the cenote.

Here I am on my final sidemount certification dive, sporting some stylish pink fins.

Out of the four courses that traditionally comprise the path to becoming a certified cave diver (Intro to Tech > Cavern > Introductory Cave > Full Cave), the cavern course is usually the longest and most challenging. If Intro to Tech is all about laying a groundwork of safety procedures and physical control while underwater (the 11ft depth number on my computer will be forever seared into my brain), cavern begins introducing all the intellectual skills that will keep January and I from getting into trouble. Skills like running a personal guideline into the overhead environment, mapping a cave system and using it to plan our dives, and doing a zero visibility air-share and exit from the cavern - all while continuing to perfect the trim and buoyancy control that we learned in Into to Tech. This is where the fun really starts. We finally get to start training full-time down in the cenote itself, instead of spending most of our time in the open water "pond" at the surface. 

Loading up the truck for another day.

At this point we're in the water for nearly six hours a day, in addition to academic lectures in the classroom, land drills, and any time spent working on equipment. We try to stay in the shade while prepping our gear for the dives, but the heat and the misquotes are inescapable. By the time I hit the water I've sweated enough in my drysuit that I'm nearly as wet inside as I am outside. The 76 degree water is a welcome relief. These are long, tiring days, but very rewarding all the same.

There is a lot of reading to do.

So what is the difference between a cavern and a cave? The cavern zone is anywhere that we can still see daylight from the surface (even if it's very faint) and we are no more than 200 continuous feet from open water (i.e. an exit from the overhead). It sounds limiting at first, but in Mexico the number of cenotes in a relatively small area means that we can "link up" multiple cenotes by swimming through the caves from one to the next. This allows for longer dives while not violating the daylight/200ft rule. 

January following the guideline back to open water. 

In Cenote Chikin Ha, we dive down under a large limestone overhang and through a tunnel that opens into a huge chamber strewn with pockmarked boulders. On the far side, 40 feet above us, beams of blue light from the neighboring cenote entrance cut through the darkness. We make our way along the guideline through the shimmering halocline, where fresh and salt water meet, forming a shimmering plane that reflects our lights and partially obscures everything beyond until we pass through to the other side. 

One of the entrances to Cenote Chikin Ha.

However, just because we can see daylight in the distance doesn't mean we can surface there in an emergency. Many caverns have small keyholes in the ceiling that allow sunlight in, but they would likely do us absolutely no good if we tried to surface through them. From a safety and training point of view, we must use the same level of caution in the cavern as we would in a cave.  

We need a lot of equipment for cave diving and there's always a chance that something might eventually break. To help minimize the risk of a "catastrophic failure" (i.e. a situation where something breaks and as a result you die), it's standard practice to carry at least two of anything important. We dive with two tanks, two sets of regulators, two masks, two cutting devices, three or more flashlights, two computers, and two forms of buoyancy control (usually a wing and a drysuit). 

January at one of our post-dive debriefs.

It may seem like overkill at first, but it's hard to understand how far away the surface really is until you're down there, swimming through the dark, just you and your buddy. There's no calling time-out if you get scared, there's no one waiting around the next turn to give you a hand if something goes wrong. It all comes down to your ability to plan for the contingencies and execute your training when it really matters. And it's all worth it to glimpse the beauty of these hidden worlds.